1. Field of the Invention
The invention concerns the reaction of a halogenated olefin having at least two halogen atoms attached to the olefinic carbons with HF in the presence of TaF.sub.5 or NbF.sub.5 to produce a fluorinated alkane.
2. Prior Art
U.S. Pat. No. 2,439,299 issued Apr. 6, 1948 to R. S. Hovey shows a fluorination reaction wherein TiF.sub.4 is a catalyst and the starting material is a halogenated alkane.
U.S. Pat. No. 2,560,838 issued July 17, 1951 to R. C. Arnold discloses boron trifluoride as a catalyst to promote the addition of anhydrous HF to olefinic compounds such as tetrachloroethylene.
U.S. Pat. No. 2,724,004 granted Nov. 15, 1955 to M. R. Frederick shows SbCl.sub.5 or SbF.sub.3 Cl.sub.2 as fluorination catalysts for the reaction of tetrachloroethylene with HF.
Canadian patent 675,615 issued Dec. 10, 1963 discloses the use of a fluoride of a metal of the group vanadium, chromium, manganese, iron, cobalt, nickel, titanium and silver as a fluorination catalyst.
V. A. Legasov et al. in Russian Journal of Inorganic Chemistry 17 (9) 1256-58 (1972) show the reaction of xenon difluoride with carbon tetrachloride in the presence of TaF.sub.5.
Chem. Abstracts 77, 4863 w (1972) shows the use of NbF.sub.5 and I.sub.2 in converting tetrafluoroethene to pentafluoroethyl iodide.
The processes of the prior art where a halogenated olefin is used as starting material and BF.sub.3 or SbCl.sub.5 are used as catalysts are deficient in that the yield of the more highly fluorinated alkanes is not as high as could be desired. Also, these catalysts require special handling since BF.sub.3 is a gas and SbCl.sub.5 is a fuming, highly hygroscopic liquid. The latter also has a relatively short catalyst life since it readily converts to inactive SbCl.sub.3.